Statistical characterization of the mobility edge of vibrational states indisordered materials

We present a conceptually simple method for determining the mobility edge o f vibrational states in disordered systems. The method is based on the conn ection between the :Level statistics of the spectrum (according to the rand om matrix theory), and the physical properties of the states. As only the l evel statistics is needed, the calculation of the eigenvectors is not requi red, thus reducing the computational effort. We apply our method to the one -dimensional case, for which a universal function for the mobility edge is obtained. [S0163-1829(99)08225-9].